The present invention is directed generally to machine control and, particularly, to an engraving tool manipulating method and apparatus.
In the past, engravers have practised their trade using manually controlled engraving tools. Early engravers formed patterns and letters on a particular work piece in free hand. Eventually, the pantograph was developed in which templates bearing the characters and symbols of a particular font style were used to guide the engraving tool. In the pantograph, the engraving tool is positioned over the work piece and is attached by an arm to a tracing pin. A template of the copy or information which is to be engraved on the work piece is set up on a separate surface using the template forms. As the tracing pin traces the outline of each letter in the set up copy, the engraving tool is guided over the work piece in the corresponding pattern. In this manner, the patterns of the copy set up are transferred to the work piece.
Even with the advent of the pantograph, engraving remains no less an art. This is because engraving requires not only the precise reproduction of font styles on the work piece, but also an aesthetically pleasing positioning of the various lines and symbols within the work piece. In the past, an engraver's ability to generate a satisfactory product was a function of numerous years of experience and experimentation. In the usual engraving task, the engraver creates the layout and selects the font style intuitively. It is only after this intuitive creation is engraved on the workpiece that any errors or imbalances will appear. For example, should the engraver have miscalculated the length of a line of copy for a given character height and font style, the whole job would have to be started over. Alternatively, the engraver could reduce the line heights which in turn will reduce copy line width. This, however, can destroy the balance of the layout. The engraver can also resort to abbreviations, but at the expense of eliminating copy which was originally sought to be engraved. In the actual engraving of the copy onto the workpiece, stylus slips errors can occur at any time, and often appear after a substantial amount of engraving has already been completed creating costly scrap. Often, the engraver discovers, after finishing the piece, that the line spacing that was selected left an overall imbalance in the appearance of the piece. Flourishes are often used to fill in the extra space. It is not unusual, when a large number of similar pieces are being engraved, with only a portion of the copy being changed for each piece, to suddenly come across a name, for example, which is too long for a given character height, workpiece width and font style chosen. In such a situation the engraver could redo the layout using a different font style, or engrave the new copy in a smaller font style. In either case the appearance of the piece will be noticeably changed with respect to the other pieces.
Additionally, if there is a large amount of copy which is to be transferred to the work piece, the number of lines which can be set up at any one time is limited by the number of letters of the particular font style which is on hand. In such case, the full layout and copy cannot be set up thereby hindering checks for errors or miscalculations in the layout.
In the machining art, chunks of metal are drilled, lathed, milled and cut to form finished mechanical parts. Often, the machines used in these operations are controlled numerically. Typically, these numerical control (NC) machines accept a paper tape, for example, upon which is located a number of coded instructions. These instructions are a sequence of codes, each code causing the machine to move in a particular direction. Alternatively, magnetic tape, electronic memory or the like can also be used to hold these instructions.
These control tapes are typically developed in the following manner. A programmer, upon examining a model part and reviewing the machine steps necessary to form such a part, transcribes the operations into a sequence of machine movements. This sequence of machine movements are then transferred to the tape in coded form. NC machines have primary application in heavy industry and are typified by a large physical size, high cost, and complexity. Additionally, a significant amount of experience and/or training is required to produce a competent NC programmer. As such, NC machines and the engraving arts are incompatible, both from the standpoint of the expense involved and the complexity of adapting and operating such a machine in a typical engraving application.